Friction elements of machines subjected to heavy loads

ABSTRACT

Metallic friction elements of machines sliding one against the other, one of which has a friction surface coated with a layer of molybdenum applied by metallization, the friction surface of the other element being coated with a layer of copper, characterized by the fact that the layer of copper is also effected by metallization.

United States Patent Caubet 1 Apr. 25, 1972 54] FRICTION ELEMENTS 0FMACHINES 3,010,843 11/1961 Eder "117/105 x SUBJECTED T0 HEAVY LOADS3,425,112 2/1969 Roemer 2,320,830 6/1943 Ricardo et al... [721 InventJacques Jean Sam-Blame, 2,787,503 4/1957 Palsulich et a1 ..308/341France [731 Assignees: Automobiles M. Berliet, Lyon, France; FOREIGNPATENTS OR APPLICATIONS Hy mm iq El Frottement, n 1,120,835 12/1961Germany ..117/237 Etienne France 705,067 3/1954 Great Britain [221Filed: May 1,1968 OTHER PUBLICATIONS [21] APPINO': 725900 Handbook ofChemistry and Physics, 42nd Ed. Cleveland,

- Ohio, Chemical Rubber Publishing Co., 1961., p. 2.156. [52] U.S.C1...117/105, 29/1495 PM, 117/131,

308/237, 303/240 Primary Examiner-Alfred L. Leavitt [51] Int. Cl. ..C23c7/00, F16c 17/12 i r x min C- K- eiff n h [58] Field of Search........308/237, 240, 241; 117/71 M, Attorney-Stevens, Davis, Miller MOSheI117/105, 131, 160, 130; 29/148.4 L, 149.5 PM,

149.5 s, 149.5 B, 149.5 c [5 ABSTRACT Metallic friction elements ofmachines sliding one against the [56] References cued other, one ofwhich has a friction surface coated with a layer UNITED STATES PATENTSof molybdenum applied by metallization, the friction surface of theother element being coated with a layer of copper, 2,329,483 9/1943Queneau et a1 ..308/237 chat-tailed by the fact that the layer f copperis 1 f 2,588,421 3/1952 Shepard ..117/71 M fected by metalhzatioh2,588,422 3/1952 Shepard ..117/71 M X 2,854,597 9/1958 Foote et a1..117/71 M X 8 Claims, No Drawings FRICTION ELEMENTS F MACHINESSUBJECTED TO HEAVY LOADS It has already been proposed to produce a pairof metallic friction elements of machines, sliding one on the other orrotating one inside the other, in such manner that the friction surfaceof one of the elements is covered with a coating of molybdenum and thatthe friction surface of the other element is essentially constituted bya cupreous metal.

It has also been proposed to form the coating of molybdenum bymetallization, the layer of cupreous metal being obtained byelectrolysis, and also to form the element to be coppered from a metalwith a low Youngs modulus such as a light metal.

According to the present invention, the cupreous metal is a deposit ofcopper obtained by metallization by' means of a metal-spraying gun.

The improvement obtained by making the metallized deposit instead of theelectrolytic deposit of copper consists of a better fixing of the copperdeposit on the surface of the metallic base.

In addition, the metallization has the effect of obtaining a combinationof copper and copper oxide, which improves the friction qualities withrespect to the other element which has been given a coating ofmolybdenum, also by metallization. The surfaces obtained bymetallization may be employed in the rough state or machined orotherwise treated with or without grinding.

Finally, before putting into service, an initial greasing can beeffected by molybdenum bisulphide in the form of a hypermicronized drypowder or in the form of powder of, appropriate granular size insuspension in an oil.

In a non-limitative example of the improvement according to theinvention, the segments of the piston of a gas engine of 1.50 m. indiameter were metallized with copper until a layer of 0.3 mm. inthickness was obtained, this layer not having been ground. The boring ofthe engine cylinder lining subjected to heavy loads was given a coatingof molybdenum of 0.5mm. in thickness, applied by metallization and nothaving been subjected to grinding. This metallization was carried outwith great care, in particular following preheating to 80 C., andsand-blasting.

After 20,000 hours working, the wear both of the liner and of thesegments was extremely small and did not exceed 0.2 mm., that is to sayonly one twentieth of that observed on similar parts which had not beensubjected to the surface treatments according to the invention.

Another example of embodiment consists of a two-cylinder uraniumfluoride compressor, of which the two crank bearing surfaces on thecrankshaft were metallized, one with molybdenum and the other withcopper. The bores of the two crankrods were also metallized, one withcopper and the other with molybdenum. After grinding, the thickness ofthe four layers deposited with a spraying gun was 0.3 mm.

The crank-rod metallized with copper was mounted on the crank-shaftbearing surface metallized with molybdenum, while the crank-rodmetallized with molybdenum was mounted on the bearing surface of thecrank-shaft metallized with copper.

The assembly was rotated for several hundred hours at 400 r.p.m. with aninitial clearance of 0.02 to 0.03 mm. No appreciable wear could bedetected.

An initial greasing of the bearing surfaces was carried out withmolybdenum bisulphide. No periodic greasing was effected subsequently.The same results were obtained for the two crank-rods. It should benoted that the surface treatments resulted in a reduction of noiseduring working of the compressor.

Finally, it is also possible to produce the element to be coppered bymetallization from a metal having a low Young's modulus, such as a lightmetal or light alloy.

For example, if a shaft is to be rotated in a bearing under doubtfulconditions of lubrication, or without any lubrication, the shaftmaterial to be adopted will be carbon steel tempered beforemetallization, while the ring will be turned from a light alloysubsequently coated with copper by metallization.

The low Young's modulus of the light alloy permits the provision ofsupporting surfaces capable of more extensive elastic deformations, andthus renders the bearings less sensitive to possible misalignments ofthe machines.

According to the invention, it is possible still further to increase toa considerable extent the resistance to wear of the elementsconstituting the frictional pair, when the surface coated with a porouslayer of molybdenum by projection with a spraying gun is subjected,after grinding, to impregnation with hardenable plastic material byclose reticulation. This plastic material must be capable of applicationunder vacuum, cold or hot, in the liquid or syrupy state, on the surfaceof the porous molybdenum, the reticulation being efiected by heat and/orby means of a catalyst or hardening agent.

Use will preferably be made of epoxy resins which, in addition to givinga considerable improvement in the friction conditions, have a goodchemical inertia and protect the supporting metal coated with molybdenumvery effectively against corrosion.

Thus, for example, if a shaft is to be rotated in a bearing in theambient air or in water, there will be chosen a shaft coated withmetallized molybdenum, ground, and then impregnated with epoxy resin,while the ring will be of solid copper. The filling-up of the porousstructure of metallized molybdenum provides an effective protectionagainst corrosion of the metal support which can then be chosen ofsemi-hard steel, and thus renders the articulation insensitive tocorrosion effects.

The example which follows brings out clearly the advantag of theinvention.

The friction pairs are universal joints for lorries. The parts areconvex and have a diameter of 40 mm.; they are made from temperednon-alloyed construction steel having the following standardcomposition, expressed in percentage by weight: C 0.42 to 0.48, Mn 0.5to 0.8, Si s 0.40, P s 0.04, S i 0.035 and S P 0.065. They were coatedby metallization with a layer of 0.1 mm. of molybdenum. The concaveparts in which the convex parts were fitted were cups of solid extrudedcopper.

In a first series of tests, the convex parts oscillated at a frequencyof one cycle per second from to 20 between the cups, the joints workedin the dry state without any incident while immersed in water loadedwith mud for 1,000 hours under a lateral pulsating load of 10,000 N.

In a second series of tests, there were subjected to the sameconditions, universal joints in which the convex parts coated withmolybdenum were ground and then impregnated under a vacuum of 5 X 10.mm. Hg of 7828 A epoxy resin according to the present invention. Now,the universal joints thus treated were able to work without incident forat least 1,500 hours, that is to say for a period 50 percent greaterthan that of the previous tests.

I claim:

1. Metallic friction elements of machines sliding one against the other,one of .which has a friction surface constituted by a sprayed porousmolybdenum layer, the friction surface of the other element beingconstituted by a sprayed copper layer.

2. Metallic friction elements according to claim 1 further comprising ahyper-micronized dry powder of molybdenum bisulphide thereinbetween aslubricant.

3. Metallic friction elements according to claim 1 further comprising amolybdenum bisulphide powder in suspension in an oil thereinbetween aslubricant.

4. Metallic friction elements according to claim 1, wherein the copperlayer is on a metal having a low Youngs modulus.

5. Metallic friction elements according to claim 4, wherein said metalis selected from the group consisting of aluminum and aluminum alloys.

6. Metallic friction elements according to claim 1, wherein at least oneof the two friction surfaces has a ground finish.

7. Metallic friction elements according to claim 6 wherein the frictionsurface having the ground finish is the molybdenum layer, said groundmolybdenum layer having a plastic material impregnated therein, saidplastic material having a close reticulation.

8. Metallic friction elements according to claim 7, wherein said plasticmaterial impregnation is an epoxy resin. 5

7 53? UNITED 51117135 PATENT OFFICE:

CERTIFICATE OF, CORRECTION Patent No. 3 658,576 C Darod A ril 25, 2. IInventor(s) Jacques Jean Caub e vt" I It is cortified that error appearsin the 'above-ideniiffed patent I and that said Letters Patent arehereby 'corr-ected as shown below:

The benefit of the filing'date of- Frefich Application I No. P.V.105.334'bf Mayv 5, 1967, is claimed:

. Signed and sealed this 5 y of September (SEAL) Attest: I v

EDWARD PLFLEI'JkIErLJR. ROBERT GOTTSCHALK 7 At to sting OfficerCommissioner of Patents

2. Metallic friction elements according to claim 1 further comprising a hyper-micronized dry powder of molybdenum bisulphide thereinbetween as lubricant.
 3. Metallic friction elements according to claim 1 further comprising a molybdenum bisulphide powder in suspension in an oil thereinbetween as lubricant.
 4. Metallic friction elements according to claim 1, wherein the copper layer is on a metal having a low Young''s modulus.
 5. Metallic friction elements according to claim 4, wherein said metal is selected from the group consisting of aluminum and aluminum alloys.
 6. Metallic friction elements according to claim 1, wherein at least one of the two friction surfaces has a ground finish.
 7. Metallic friction elements according to claim 6 wherein the friction surface having the ground finish is the molybdenum layer, said ground molybdenum layer having a plastic material impregnated therein, said plastic material having a close reticulation.
 8. Metallic friction elements according to claim 7, wherein said plastic material impregnation is an epoxy resin. 